This application claims the priority benefit of Taiwan application serial no. 88117224, filed Oct. 6, 1999.
1. Field of the Invention
This invention relates to a structure of a vacuum display device, and more particularly to a reinforced structure to strengthen the structure of a high voltage vacuum fluorescent display (HVVFD), and a reinforced structure to strengthen the structure of a high voltage vacuum fluorescent electrode.
2. Description of Related Art
The vacuum device has been a very popular product in the market for a long time. Its range of application is very wide, for example, display devices, stereos, etc. Display devices with high luminosity have been widely used in many situations for forwarding information, for instance, a scoreboard in a stadium, an electronic digital display in a public area, a bulletin board on highway for showing directions and road conditions, etc. The display screen used in a large electronic digital display is a display technology consisting of many small light-emitting devices. Today, such small light-emitting devices include incandescent light bulbs, small cathode ray tubes (CRT), high voltage vacuum fluorescent displays (HVVFD), small fluorescent lamps, and light-emitting diodes (LED). Among these five light-emitting devices, CRT, HVVFD and LED can be used in a large screen for displaying animated color images.
CRT uses an electron beam to bombard a fluorescent powder which then emits light. This method of emitting light is very efficient. An electron gun is used to generate the electron beam, wherein the electron beam is generated by heating beryllium oxide, strontium, and calcium coated on a metal. The heating excites the electrons which then are accelerated by being passed through an electron lens. A high degree of vacuum state must be maintained in the cathode ray tube since air molecules would retard the efficiency of the bombardment from the electron gun and the free ions generated by the bombardment would damage the electron gun. In order to maintain the high degree of vacuum state, the glass from which the tube is fabricated must have a certain thickness so as to be strong enough to sustain the atmospheric pressure. At the same time, since the electron gun is a kind of point electron source that makes use of a scanning method to bombard the fluorescent powder, the larger the screen, the longer a distance between the gun and the screen must be. For this reason, the CRT is usually bulky and heavy. FIG. 1 is a perspective view of a high voltage vacuum fluorescent display (HVVFD) according to the prior art. HVVFD 100 uses a line electron source 102, as opposed to the point electron source used in a CRT. Since the line electron source 102 uses a tungsten filament coated with oxide that emits a lot of thermoelectrons for bombarding the fluorescent powder, the disadvantage of the CRT being too bulky can greatly be improved thereby. At the same time, since HVVFD 100 can coat the three original colors, red, green and blue, on one light-emitting unit 104, it is easier to combine into a color display screen. In comparison with a small CRT, the resolution of the HVVFD is also higher. The line electron source 102 emits thermoelectrons, which pass through the gate 106 to be accelerated, and finally bombard the light-emitting unit 104. The line electron source 102, gate 106 and light-emitting unit 104 are together enclosed in a vacuum space formed by a glass housing 108. The degree of vacuum state required is 10xe2x88x926-10xe2x88x927 torr. The lead wires 112 for the line electron source 102, gate 106, and light-emitting unit 104 protrude through the wire leading tube 110 on the back side of the glass housing 108.
Currently, the commercial large display screen for displaying animated images mainly employs small CRT and HVVFD, and since CRT and HVVFD are both vacuum devices, the rigidity of the glass structure used by both of them needs to be able to sustain atmospheric pressure. For example, the 80xc3x9780 mm2 HVVFD needs at least a 2.8 mm thickness of glass in order to sustain atmospheric pressure. For this reason, there is a 5.6 mm (2.8 mmxc3x972) of edge space for each device that must be excluded from the image display; therefore, the resolution of the display device is limited.
Another limitation is the way in which wires for the electrodes exit the glass housing. Because CRT uses the electron gun scanning method, only several electrodes need exit from the electron gun since the electrodes are simple in disposition. But since the HVVFD uses an X, Y matrix drive, the number of electrodes required is at least the sum total of X and Y, and if these electrodes were to exit, the space to be excluded for display would cover all the space occupied by the electrodes. The wire exiting method of today""s commercial HVVFD is to bring the wires out from the base glass plate by drilling holes in the base glass plate instead of allowing the wires to protrude through the edges of the device. In this case, the process of drilling holes through the glass is rather difficult and complicated. In the meantime, in order to preserve the vacuum state of the device, the areas where wires exit must be sealed with special material employing special techniques. This makes the fabrication difficult and expensive. Additionally, the number of X and Y drives is limited; if not, the base plate with a large number of holes would cause difficulty during element printing on the base plate.
It is therefore an objective of the present invention to provide a structure of a vacuum display device that can use a relatively thin plate of glass, while simultaneously making use of a reinforced structural design to increase the rigidity of the glass housing in order to sustain a high pressure.
It is another objective of the present invention to provide a structure of a vacuum display device that allows the wire electrodes to exit through the edges of the device in order to reduce the thickness at the edges and simultaneously simplify the fabrication process.
In accordance with the foregoing and other objectives of the present invention, a structure of a vacuum display device is provided. The structure mainly comprises a vacuum chamber, the enclosure of which is formed by a surface plate, a base plate, and a spacer plate. The surface plate includes a display matrix and a black matrix and the base plate includes an inner surface and an outer surface, the base plate possesses a plurality of recesses in its edges. The required electrode lead wires are disposed on the inner surface of the base plate and extended out through the recesses. A multiple number of fins are disposed on the spacer plates to support the surface plate, the base plate, and the spacer plate, and are located at the black matrices. Additionally, a sealing material is used to seal the connecting edges between the surface plate, the base plate, and the spacer plate, and is also used to fill the gaps in the recesses.
According to a preferred embodiment of the present invention, fins are used to reinforce the structure of the vacuum device so that the thickness of the spacer plates can be reduced to leave more room for increasing the resolution when the device is fabricated. Moreover, since the electrode wires exit through recesses at the edges of the base plate, it is not necessary to increase the thickness of the spacer plates for the wiring. This also simplifies the fabrication.